Sildenafil versus vasopressin in persistent pulmonary hypertension of the newborn

Abstract EN

Background : PPHN is a complex syndrome characterized by failure of the pulmonary vasculature to relax at birth and consequently of the normal adaptation to extra uterine life of the fetal heart / lung system, resulting in hypoxemia.

The treatment for PPHN has evolved over the past 10 to 15 years but reported mortality remains at 10 % to 20 % in newborns with PPHN.

Finding an effective and selective pulmonary vasodilator with little or no adverse effects for the treatment of PPHN has been elusive over the past 20 years.

Aims : to evaluate the role of sildenafil and vasopressin in treatment of pulmonary hypertension of the newborn and which of them is more beneficial.

Methods : 20 term or post-term gestation (> 37 weeks' gestation and < 28 days), (age range 2-4 days, mean age 3.2 + .7 days, 18 males and 12 females) with severe hypoxemia and primary or secondary pulmonary hypertension diagnosed by clinical findings and confirmed by echocardiogram.

10 cases included in each of the sildenafil and vasopressin treated groups.

The infants had to be on mechanical ventilation with an oxygenation index (01) > 40, show clinical signs of severe refractory hypoxemia.

The echocardiogram performed before entry had to show evidence of right-to-left shunt (post-ductal 02 saturation was 10 % lower than the pre-ductal measurement) and estimated pulmonary artery pressures > 40 mm Hg.

Arterial blood gases were monitored from an umbilical arterial catheter, and 01 was calculated in every arterial blood gas using the Pa02 from the umbilical arterial catheter.

Echocardiography was used as an estimate of pulmonary blood flow, Systolic and diastolic pulmonary artery pressures (PAP) were evaluated by measuring pressure gradients through the DA with the simplified Bernouilli formula.

Results: In both treatment groups, oxygenation improved in all of the infants sometime between 2 and 48 hours after initiation of treatment.

The mean 01 at entry was 60 (± 12.

8) in the sildenafil group and 59 (+ 10.

5) in the vasopressin group with low Pa02; 38.2 (+ 12.

5) mm Hg and 41.

7 (+ 11.

3) mm Hg, respectively.

In vasopressin group; all values in 2 hours and 48 hours were significantly lower than those of the sildenafil group._Echocardiography revealed that Pulmonary artery pressure (PAP) steadily improved in both Sildenafil and vasopressin groups.

However, the 2 hours and 48 hours values of the vasopressin group was significantly higher than those-of--the sildenafil group the start values but insignificantly differ from each other.

Forty-eight hours after sildenafil or vasopressin treatment, echocardiography revealed that and the contractility of both ventricles improved, indicating a marked reduction in pulmonary arterial pressure.

Arterial blood pressure steadily improved in both Sildenafil and vasopressin group.

However, the 2 hours and 48 hours values of the vasopressin group were significantly higher than those of the sildenafil group.

Conclusion: The findings of our study suggest that oral sildenafil and to a less degree vasopressin may be survival jackets in cases of PPHN.

Sildenafil therapy is well tolerated and appears to be safe in patients with pulmonary hypertension.

Sildenafil may not be as effective in certain causes of PPHN such as sepsis.

Vasopressin is most beneficial in PPHN in combination with low systemic vascular resistance.